Mario Balotelli's agent Mino Raiola has said the striker is "as valuable as the Mona Lisa".
The Manchester City striker is regularly linked with a move back to Italy and AC Milan president Silvio Berlusconi fuelled further rumours this week by confirming his interest in the 22-year-old.
When asked to comment on rumours of a mooted bid for Balotelli in January, he told Sky Sport Italia: "No, it's not a dream. I never dream."
But Raiola, who counts Zlatan Ibrahimović as one of his clients, suggested the 23-year-old was out of the Rossoneri's reach.
"No Italian club would be able to afford him. Balotelli is as valuable as the Mona Lisa," he told Sky Italia. The Mona Lisa was last insured for $768m
"And City have been very clear - they don't want to sell."
Milan head coach Massimiliano Allegri is a confirmed admirer and also hinted his desire to see Balotelli return to the city.
"(Balotelli) is a great player with extraordinary physical and technical qualities," Allegri said. "However, given his qualities, I believe he has thrown away a few years of his career."